CDC Advises State Departments of Health on Zika Control Efforts

In an effort to contain the Zika virus, the Centers for Disease Control and Prevention (CDC) is holding a series of teleconferences regarding concerns that were raised during the Zap Zika conference held in early April. The fifth conference in the series discusses Zika epidemiology.

Thus far, the CDC has held Zika preparedness teleconferences regarding communication and infection-related birth defects, among others.

The Zika virus has been circling the Americas since 2015, with the first locally-transmitted case reported in Brazil in May of that year. From May 2015 to June 2, 2016, local transmission of the virus has been reported in 39 countries and territories in the Americas. On the teleconference, Marc Fischer, MD, MPH, chief of Surveillance and Epidemiology activity in the Arboviral Disease Branch, Division of Vector-Borne Diseases at the National Center for Emerging and Zoonotic Infectious Diseases of the CDC warned that “further spread of the virus to other countries in the region, is likely.”

Countries with local transmission of the Zika virus have been reporting the number of cases to the Pan American Health Organization since January 2015. From January 2015 to May 2016 the highest number of cases, a total of 194,263 suspected and confirmed cases which would account for 47% of all cases in the region, was reported by Brazil, the site of the 2016 Olympic and Paralympic Games. Recently, both healthcare professionals and athletes have expressed concern over the spread of Zika through the Games.

During the teleconference, Dr. Fischer discussed state and local department of health (DOH) preparedness. Thus far, there has been no local transmission of the Zika virus in the United States; however, there have been many travel-related cases, most of which have been identified in New York City and the state of Florida, with 146 and 143 cases respectively. Retrospective reporting may change these trends, according to Dr. Fischer.

Since surveillance is the key to controlling the virus, and preventing outbreaks, the CDC has broken down surveillance into several phases:

0. Pre-incident Preparedness

• State DOHs are expected to assess the situation, educate the public as well as healthcare providers, and establish lab testing capacity. According to Dr. Fischer, all states should have already completed this phase.

1. Mosquito Season

• DOHs are asked to investigate possible Zika infection cases by first testing them and then assessing the mode of infection (local, travel-related, through sexual intercourse, or through blood transfusion). The CDC recommends testing those individuals who are symptomatic during or within two weeks of travel to areas with local transmission, specifically pregnant women, as well as those who have epidemiological risks. Once Zika or related congenital infections have been lab confirmed, healthcare providers must notify their local or state health departments, who will then report the cases to the CDC.

2. Limited Local Transmission in One Geographic Area

• All lab-confirmed cases must be investigated to identify areas where local transmission is most likely to occur. Household members and neighbors of patients (within a 150-yard radius) are to be surveyed. Individuals who present with Zika-related signs and symptoms are to be tested for Zika or other diseases which can be mistaken for the virus, specifically those with increased febrile or rash illnesses. Local healthcare providers and laboratories are to be notified of the case. The CDC suggests conducting community outreach to increase Zika awareness and prevention methods. All blood donors are to be screened, and mosquito surveillance measures are to be taken.

​​3. Widespread Local Transmission in One Geographic Area

• Case investigations are to be conducted to identify focus areas and target infection control.
• Additional cases should be investigated to determine whether they are incidences of local transmission or are related to previous cases.
• Surveillance efforts should be expanded to encompass all areas with cases.
• All pregnant women should be screened and those testing positive for the virus or are suspected of being infected, should be monitored.
• All blood donors are to be screened.

​4. Widespread Local Transmission in Multiple Areas

• The CDC recommends that all previously implemented surveillance efforts be intensified for intensity and the geographical extent of transmission.
• Those who are at highest risk for Zika-related complications should be tested.
• Areas experiencing local transmission should be identified. Prevention and control efforts should be intensified in these areas.
• State and local departments of health should collaborate with mosquito control districts, commercial laboratories, blood collection agencies, and the CDC, as well as other federal agencies.

Timely reporting and assessment of all cases is key to reducing the risk of local transmission, according to Dr. Fischer. State and local health departments are encouraged to email preparedness@cdc.gov with any questions regarding Zika epidemiology, or any other concerns regarding preparedness and response.